not that easy unless you have a firm unix or linux background, and are capable of using the terminal.[/url]
yeah, using that keyboard thingy is tricky... it hurts the tips of your fingers if you don't do it right

In my experience, you don't actually need to use the terminal to get this job done, it's all point&click. when Ubuntu Linux is all set up, there aren't those many situations when you need the terminal, what you do have is the option to use it if you prefer.
As for the instalation procedure: the partition manager that is used with Ubuntu Linux for x86 computers works better than the one for PPC. Unfortunately I won't be able to get in to much detail about that as I never installed linux on a x86 Mac, only PPC and x86 "normal" PCs.
On my Powerbook G4 I had to:
1) set up the partitions with the Ubuntu CD, so that it would create the right combination of boot partitions, yaboot loader partition, one for Linux swap, one for OS X and the last one for Linux itself.
2) cancel the setup after partitioning/formatting is done
3) set up OS X on its specific partition (mine: 30GB)
4) set up Linux on its partitions (25GB for / , 1GB for Swap)
I tried to have a FAT partition there as well to ease the transfer of files between OSs but I couldn't get it to work, as the Mac partition tables seem to be different than the ones I know from the DOS world. this is less of a concern as there are extensions to OS X that allow EXT2 read/write and Linux can mount HFSplus partitions. This way I can put files on /Users/Shared on the OS X side and fetch them when I boot with Linux. The opposite also works.
Hope this helps!
Nuno